@import url('https://fonts.googleapis.com/css2?family=Plus+Jakarta+Sans:wght@300;400;500;600;700&display=swap');

:root{
  --ink:#000000;
  --paper:#ffffff;
  --glass:rgba(255,255,255,.72);
  --r:18px;
  --maxw:1200px;
}

*,*::before,*::after{box-sizing:border-box}

html{
  scroll-behavior:smooth;
  -webkit-text-size-adjust:100%;
}

body{
  margin:0;
  padding:0;
  color:var(--ink);
  background-color:var(--paper);
  background-image:radial-gradient(rgba(0,0,0,.09) 1px, transparent 1px);
  background-size:20px 20px;
  font-family:'Plus Jakarta Sans', system-ui, -apple-system, 'Segoe UI', 'PingFang SC', 'Hiragino Sans GB', 'Microsoft YaHei', sans-serif;
  font-size:16px;
  line-height:1.7;
  font-weight:400;
}

img{max-width:100%;height:auto;display:block}

a{color:var(--ink);text-decoration:underline;text-underline-offset:3px}
a:focus-visible{outline:2px solid var(--ink);outline-offset:3px}

.wrap{
  width:100%;
  max-width:var(--maxw);
  margin:0 auto;
  padding:0 20px;
}

/* 顶部细条 */
.strip{
  background:var(--ink);
  color:var(--paper);
}
.strip-in{
  display:flex;
  align-items:center;
  justify-content:space-between;
  gap:14px;
  min-height:42px;
  padding-top:6px;
  padding-bottom:6px;
}
.strip-brand{
  font-size:16px;
  font-weight:600;
  letter-spacing:.14em;
  line-height:1.4;
}
.strip-dots{
  width:88px;
  height:10px;
  background-image:radial-gradient(#ffffff 1.2px, transparent 1.2px);
  background-size:10px 10px;
  opacity:.8;
}

/* 页头 */
.masthead{
  position:sticky;
  top:0;
  z-index:50;
  background:rgba(255,255,255,.88);
  backdrop-filter:blur(12px);
  -webkit-backdrop-filter:blur(12px);
  border-bottom:1px solid var(--ink);
}
.mast-row{
  display:flex;
  align-items:center;
  gap:14px;
  padding-top:10px;
  padding-bottom:10px;
}
.brandmark{
  flex:0 0 auto;
  width:44px;
  height:44px;
  display:inline-flex;
  align-items:center;
  justify-content:center;
  border:1px solid var(--ink);
  border-radius:50%;
  text-decoration:none;
  background:var(--paper);
  transition:background .22s ease, color .22s ease;
}
.brandmark:hover{background:var(--ink);color:var(--paper)}
.brandmark-img{width:26px;height:26px;object-fit:contain}
.brandmark-txt{font-weight:700;font-size:18px;line-height:1}

.caps{flex:1 1 auto;min-width:0;display:flex;justify-content:flex-end}
.caps ul{
  display:flex;
  gap:8px;
  list-style:none;
  margin:0;
  padding:4px 0;
  overflow-x:auto;
  scrollbar-width:none;
  -webkit-overflow-scrolling:touch;
}
.caps ul::-webkit-scrollbar{display:none}
.caps li{flex:0 0 auto}
.caps a{
  display:inline-flex;
  align-items:center;
  min-height:40px;
  padding:9px 16px;
  border:1px solid var(--ink);
  border-radius:999px;
  font-size:16px;
  line-height:1.35;
  text-decoration:none;
  white-space:nowrap;
  background:transparent;
  transition:background .22s ease, color .22s ease;
}
.caps a:hover,.caps a:focus-visible{background:var(--ink);color:var(--paper)}

/* 主栅格 */
.grid{
  display:grid;
  grid-template-columns:240px minmax(0,1fr);
  gap:32px;
  align-items:start;
  padding:28px 20px 56px;
}

/* 左栏 */
.rail{
  position:sticky;
  top:88px;
  border-left:2px solid var(--ink);
  padding-left:16px;
}
.kick{
  display:block;
  font-size:16px;
  line-height:1.4;
  letter-spacing:.2em;
  opacity:.55;
}
.rail-h{
  margin:2px 0 12px;
  font-size:20px;
  line-height:1.3;
  font-weight:700;
  letter-spacing:-.01em;
}
.railnav ul{list-style:none;margin:0;padding:0}
.railnav li + li{margin-top:2px}
.railnav a{
  display:block;
  padding:9px 0;
  min-height:40px;
  font-size:16px;
  line-height:1.4;
  text-decoration:none;
  border-bottom:1px solid rgba(0,0,0,.12);
  transition:padding-left .2s ease, border-color .2s ease;
}
.railnav a:hover,.railnav a:focus-visible{
  padding-left:6px;
  border-color:var(--ink);
  text-decoration:underline;
}

.main{min-width:0}

/* 首屏 */
.hero{
  display:grid;
  grid-template-columns:minmax(0,1.1fr) minmax(0,.9fr);
  gap:24px;
  align-items:stretch;
  min-height:45vh;
  margin-bottom:20px;
  border:1px solid var(--ink);
  border-radius:var(--r);
  overflow:hidden;
  background:var(--glass);
  backdrop-filter:blur(10px);
  -webkit-backdrop-filter:blur(10px);
}
.hero-copy{
  display:flex;
  flex-direction:column;
  align-items:center;
  justify-content:center;
  gap:16px;
  padding:40px 26px;
  text-align:center;
}
.hero h1{
  margin:0;
  font-size:clamp(28px,4.6vw,46px);
  line-height:1.08;
  font-weight:700;
  letter-spacing:-.03em;
}
.lede{
  margin:0;
  max-width:36ch;
  font-size:17px;
  line-height:1.6;
  opacity:.78;
}
.hero-fig{
  margin:0;
  display:flex;
  min-height:220px;
  background-color:#f2f2f2;
  background-image:radial-gradient(rgba(0,0,0,.16) 1px, transparent 1px);
  background-size:14px 14px;
}
.hero-img{width:100%;height:100%;object-fit:cover}

/* 正文章节卡片 */
.main > article:not(.hero){
  margin-bottom:18px;
  padding:28px 26px;
  border:1px solid var(--ink);
  border-radius:var(--r);
  background:var(--glass);
  backdrop-filter:blur(10px);
  -webkit-backdrop-filter:blur(10px);
  scroll-margin-top:100px;
}
.main > article:not(.hero):last-child{margin-bottom:0}

.main article h2{
  margin:0 0 12px;
  font-size:clamp(22px,3vw,30px);
  line-height:1.22;
  font-weight:700;
  letter-spacing:-.02em;
}
.main article h3{
  margin:22px 0 10px;
  font-size:20px;
  line-height:1.3;
  font-weight:600;
  letter-spacing:-.01em;
}
.main article small{
  display:block;
  margin-bottom:6px;
  font-size:16px;
  line-height:1.4;
  letter-spacing:.18em;
  opacity:.55;
}
.main article p{margin:0 0 14px}
.main article p:last-child{margin-bottom:0}
.main article ul,.main article ol{margin:0 0 14px;padding-left:22px}
.main article li{margin-bottom:6px}
.main article figure{margin:18px 0}
.main article figure img{border-radius:14px;border:1px solid rgba(0,0,0,.15)}
.main article blockquote{
  margin:18px 0;
  padding:6px 0 6px 18px;
  border-left:2px solid var(--ink);
  font-weight:500;
}
.main article table{width:100%;border-collapse:collapse;margin:0 0 14px;font-size:16px}
.main article th,.main article td{
  text-align:left;
  padding:10px 12px;
  border-bottom:1px solid rgba(0,0,0,.18);
}
.main article table{display:block;overflow-x:auto}

/* 页脚 */
.foot{
  margin-top:40px;
  padding-top:36px;
  border-top:1px solid var(--ink);
  background:var(--ink);
  color:var(--paper);
}
.foot-grid{
  display:grid;
  grid-template-columns:1.2fr 1fr auto;
  gap:28px;
  align-items:start;
  padding-bottom:28px;
}
.faddr{
  font-style:normal;
  font-size:22px;
  line-height:1.35;
  font-weight:700;
  letter-spacing:-.02em;
}
.fcol-end{justify-self:end}
.flinks{
  list-style:none;
  margin:0;
  padding:0;
  display:grid;
  grid-template-columns:1fr 1fr;
  gap:2px 20px;
}
.flinks a{
  display:inline-flex;
  align-items:center;
  min-height:40px;
  color:var(--paper);
  font-size:16px;
  line-height:1.4;
  text-decoration:none;
  opacity:.86;
  transition:opacity .2s ease;
}
.flinks a:hover,.flinks a:focus-visible{opacity:1;text-decoration:underline}
.totop{
  display:inline-flex;
  align-items:center;
  min-height:40px;
  padding:9px 18px;
  border:1px solid var(--paper);
  border-radius:999px;
  color:var(--paper);
  font-size:16px;
  line-height:1.4;
  text-decoration:none;
  transition:background .22s ease, color .22s ease;
}
.totop:hover,.totop:focus-visible{background:var(--paper);color:var(--ink);text-decoration:none}
.foot a:focus-visible{outline-color:var(--paper)}
.fbot{
  border-top:1px solid rgba(255,255,255,.28);
  padding-top:14px;
  padding-bottom:18px;
  text-align:center;
}
.fbot p{margin:0;font-size:16px;line-height:1.5;opacity:.75}

/* 动效 */
.reveal{
  opacity:0;
  transform:translateY(14px);
  transition:opacity .5s ease, transform .5s ease;
}
.reveal.in{opacity:1;transform:none}

/* 断点 */
@media (max-width:920px){
  .grid{
    grid-template-columns:minmax(0,1fr);
    gap:18px;
    padding-top:18px;
    padding-bottom:36px;
  }
  .rail{
    position:static;
    border-left:0;
    border-top:1px solid var(--ink);
    padding-left:0;
    padding-top:12px;
  }
  .rail-h{margin-bottom:10px;font-size:18px}
  .railnav ul{display:flex;gap:8px;overflow-x:auto;padding-bottom:6px;scrollbar-width:none}
  .railnav ul::-webkit-scrollbar{display:none}
  .railnav li + li{margin-top:0}
  .railnav a{
    display:inline-flex;
    align-items:center;
    white-space:nowrap;
    min-height:40px;
    padding:8px 14px;
    border:1px solid var(--ink);
    border-radius:999px;
  }
  .railnav a:hover,.railnav a:focus-visible{padding-left:14px}

  .hero{
    grid-template-columns:minmax(0,1fr);
    min-height:0;
  }
  .hero-fig{order:-1;min-height:180px;max-height:34vh}
  .hero-copy{padding:32px 20px}

  .foot-grid{
    grid-template-columns:minmax(0,1fr);
    gap:20px;
  }
  .fcol-end{justify-self:start}
}

@media (max-width:560px){
  .wrap{padding-left:16px;padding-right:16px}
  .grid{padding-left:16px;padding-right:16px}
  .hero-copy{padding:26px 16px}
  .main > article:not(.hero){padding:22px 16px}
  .flinks{grid-template-columns:1fr 1fr}
}

@media (prefers-reduced-motion:reduce){
  html{scroll-behavior:auto}
  .reveal{opacity:1;transform:none;transition:none}
  *{transition-duration:.01ms !important;animation-duration:.01ms !important}
}

button[aria-expanded]{min-width:44px;min-height:44px}